1. Field of the Invention
The present invention relates generally to a device for securing a deadbolt latch, specifically to a device which inhibits the deadbolt latch from being turned from the outside with a key.
2. Background of the Invention
There has long been a desire for people to feel more secure within a dwelling than the security they are provided with by the activation of a deadbolt lock. In houses, hotels, apartments, or any dwellings in general, bars and other physical restraints may be used to completely secure windows as they do not require constant through access. Doors, on the other hand, are much more challenging to secure because they must be opened and closed regularly.
Deadbolts are surely the industry standard for quickly and easily securing a door. As a result, thieves and other notorious professionals have developed tools and skills to “pick” or quickly and easily deactivate and thus open deadbolts from the outside, putting one's personal security at great risk.
Keys themselves also have presented a substantial problem with home security. Much of the fear and worries felt by a person whose inner dwelling security feels compromised, stems from the concern over whether or not they hold the only keys to the deadbolt locks securing their dwelling. Certainly, in the case of tenants living in rental buildings, or hotel and motel occupants, additional keys to the deadbolt locks are held by the landlord or hotel management.
Additional rogue keys may also be held by cleaning staff, repair technicians, contractors, and in the case of apartments, even previous tenants. Thus for many people there is no clear sense of security felt from merely closing a deadbolt lock.
One of the most common products used in an effort to increase entrance security is a chain, ball and sleeve, or sliding piston. None of these accessories area as strong as a closed deadbolt however, and only come into use after a deadbolt has been bypassed. As well, such devices must be screwed to the door, making them not suitable for many applications where modifications to the existing building structure are prohibited and further impractical.
Consequently, inventors have created several types of devices to restrict deadbolts from being turned by a key or other device from the outside. Most of the devices work on the principle of partially encapsulating the deadbolt finger actuator and bracing it from being turned by further engaging the shank of the doorknob. This principle forms the basis of U.S. Pat. No. 4,279,137 COOK, and U.S. Pat. No. 5,052,202 MURPHY, which disclose variations of a thin flat plate with a hole to receive the deadbolt finger actuator as well as an integrated u shaped leg to brace the deadbolt actuator with the doorknob shank. U.S. Pat. No. 5,007,263 TAYLOR, works in a similar fashion but uses a separate u shaped bar and a double slot to engage either a key or the finger actuator.
While these devices do offer an additional measure of protection, they suffer from a number of disadvantages:                (a) They are of substantial dimension in order to span the distance between the doorknob shank and the deadbolt actuator. Consequently, they are bulky and hence not very portable—generally impractical to keep in the vicinity of a door, and even less practical to transport to other rooms or buildings during work, leisure or travel.        (b) They are awkward to use. Because of the setscrew and sliding sleeve, it is not immediately readily apparent how one would engage the device to a deadbolt and doorknob assembly.        (c) They work only with certain types of common deadbolt and doorknob configurations. Each major deadbolt manufacturer has a different shaped deadbolt finger actuator, and the previously described devices will not necessarily work with all of them.        (d) They require a doorknob to be present in order to work effectively. Since some doors use the deadbolt finger lever as a doorknob, the devices will not work at all in this situation.        (e) They are comparatively complex and costly to manufacture.        
Still another type of device is described in U.S. Pat. No. 4,951,982 SORKILMO, and sold by J&L Distributors as “the Deadbolt Buddy”. This device uses wedges that slip into the small space between the deadbolt finger actuator and the deadbolt plate. A thumb set screw is used to expand the wedge and thus jam the deadbolt actuator by way of friction between the wedge and the lock plate. Unfortunately, this device though comparatively compact with respect to the previously mentioned art, still suffers from the fact it is tricky to use, as well as relatively costly and complex to manufacture. It requires a tapped sleeve, a threaded rod, a rubber foot, and is therefore considerably more complex than the previously mentioned art.
Another problem with this type of device is that the user may over tighten the plastic thumb screw and thereby inadvertently strip the threads rendering the entire device inoperable. Furthermore, if a metal screw is used to reduce the risk of stripping the threads, then the over tightening could damage or pry off the actual deadbolt actuator finger lever.